wordpress插件中的变量indise html

I am doing my first every plugin to Wordpress.

How can i insert variable between HTML? I want to insert $today_output between divs?

Have tried all sort of things, but this is too confusing to me.

      $today_post_id = 82;
      $post_content = get_post($today_post_id);
      $today_output = wpautop( $post_content->post_content);

    $output = sprintf(
        '<div%2$s class="et_pb_code et_pb_module%3$s">
            want to add today_output variable here
        </div> <!-- .et_pb_today -->',
        $this->shortcode_content,
        ( '' !== $module_id ? sprintf( ' id="%1$s"', esc_attr( $module_id ) ) : '' ),
        ( '' !== $module_class ? sprintf( ' %1$s', esc_attr( $module_class ) ) : '' )
    );


    return  $output;

Thanks, Ville

Maybe try it using string concatenation instead like this:

<?php 

    $output = '<div class="' . $classname . '">' .
                '<div>' . $content . '</div>' .
              '</div>';

?>